Terzi, Merve; Öner, Erdal; Uzun Yaylacı, Ecren; Oktay, Mine Gül; Yaylacı, Murat

Contact problems which concern the stress distribution resulting from the interaction between two elastic bodies have long been a focus of research. In the field of solid mechanics, they hold particular importance because loads are generally transmitted to deformable bodies through their points of contact. This study investigates the contact problem of a layered medium containing a homogeneous orthotropic layer and an isotropic half-plane using a multi-method approach. A rigid flat indenter is applied to the orthotropic layer with frictional effects neglected, while the influence of body forces in the orthotropic layer is taken into account. Key contact parameters such as the contact stress under the indenter, the initial separation load, and the point of initial separation are determined as part of the analysis. The study is structured into three main sections. In the first section, the problem is analytically examined based on classical elasticity theory. Within this framework, a singular integral equation governing the contact problem is derived and solved numerically. The second section presents a finite element analysis using ANSYS software to simulate the contact interaction and evaluate the stress distribution. In the third and final section, the problem is addressed through artificial neural network (ANN) techniques, offering a data-driven perspective. Ultimately, the results obtained from the analytical, numerical (FEM), and ANN-based methods are compared, showing excellent agreement across all approaches.

AtıfScopus15·WoS10·OpenAlex16

İncele

Uyar, M.

When flexible manipulators complete their movements to the desired position, vibrations occur at the endpoint. Reducing vibrations is an important advantage for eliminating positioning errors and monitoring position accuracy. However, the increase in vibration amplitudes leads to the inability to complete the planned tasks in the applications and results in loss of productivity. Therefore, the reduction of end-effector vibrations is an important research area. In this study, a motion-based control (MBC) method with designed motion profiles is introduced to reduce the endpoint vibrations of epoxy–glass-reinforced composite manipulators. Three different motion profiles, namely Modification-1, Modification-2, and Modification-3, are designed according to time and maximum velocity values depending on the system's frequencies. For the design of Modification-1, variable deceleration and acceleration times are considered, while for Modification-2 and Modification-3, both the maximum angular velocity and the deceleration and acceleration times are utilized. For two different angular positions and motion times, all motion profiles are applied to two composite manipulators with different frequencies, and the results are experimentally and numerically obtained to examine the vibration performance of MBC. Simulation results confirmed with experiments are achieved using mathematical models in ANSYS. To evaluate the effectiveness of MBC, the change in RMS values of endpoint vibration responses and the reduction rates are presented comparatively for all motion profiles. The results show significant advantages for the MBC method, reducing vibrations by approximately 99%, and eliminating positioning errors caused by vibrations.

AtıfScopus3·WoS4·OpenAlex4

İncele

Erbayrak, Engin; Yuncuoglu, Ercument Ugur; Kahraman, Yusuf; Gumus, Beril Eker

In this study, experimental and numerical investigations were carried out in order to determine the mechanical properties and impact response of hybrid composite laminate. The hybrid composite laminate was formed from plain woven carbon fiber reinforced epoxy (CFRE) and plain woven glass fiber reinforced epoxy (GFRE) fiber using VARTM (vacuum-assisted resin transfer molding) process. The mechanical properties of the hybrid composites were determined using tensile test device with a 1 mm/min loading rate at room temperature. In addition, hybrid composites were subjected to low-velocity impact test under different impact energy levels (10, 20, 30, 40 J) for determining the impact response. Moreover, mechanical properties and impact responses of CFRE and GFRE laminates were also determined to compare to those of hybrid composite (HCGFRE). Microstructure analysis was performed to investigate the damage surfaces of the fiber and matrix in the composite material subjected to impact and tensile forces. In numerical analyses, composite damage model (Mat 54) was utilized in LS-DYNA® explicit finite element program to simulate the impact behavior of CFRE, GFRE and HCGFRE laminates. Consequently, the tensile test results showed that hybrid composite laminate behaved more ductile than carbon composite laminate and it exhibited more brittle behavior than glass composite laminate. Also, it was determined that absorbed energy and impact load capacity of HCGFRE composite laminate are between absorbed energy and impact load capacity of CFRE and GFRE composite laminate. It was determined that numerical results indicate a similar tendency with the experimental results.

AtıfScopus12·WoS13·OpenAlex14

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